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圆砾泥岩复合地层中盾构微扰动施工控制是岩土工程实践中面临的难题。南宁地铁1号线盾构下穿友爱居民小组面临圆砾与泥岩复合地层的挑战,首先对泥水盾构泥浆性能指标进行优化,采用现场试验确定了富水圆砾地层袖阀管注浆加固浆液配合比;利用自动化监测系统对盾构下穿房屋的沉降进行实时监控,并借助及时通讯工具实现穿越施工中信息化施工;定义圆砾泥岩复合地层盾构开挖面内泥岩高度与盾构机刀盘直径的比值为复合比λ,分析掘进参数平均值随λ的变化规律。通过现场实测结果表明:袖阀管注浆能够有效的控制建筑物沉降,自动化监测能够实时反映盾构推进导致房屋变形,为施工反馈控制提供依据,泥水盾构在圆砾泥岩复合地层中会遇到开挖仓压力波动过大,刀盘扭矩、推力增大,贯入度降低等现象。当λ≤0.15上述现象基本不发生;当0.15≤λ<0.6时,参数平均值波动最剧烈,对沉降控制十分不利;当λ≥0.6时,扭矩和总推力进一步增大,但开挖仓压力波动情况稍弱而贯入度会进一步降低。要以盾构开挖仓压力控制为指标而非追求推进速度,提高转速、降低泥浆黏度是减少参数波动的有效手段。
The construction control of the shield micro-perturbation in the boulder-mudstone complex strata is a difficult problem in the practice of geotechnical engineering. Nanning Metro Line 1 under the shield wear friendly loving group facing the challenge of the boulder and mudstone composite strata, first of all mud slurry shield performance indicators to optimize the use of field tests to determine the water rich boulder formation sleeve valve grouting reinforcement slurry With the use of automated monitoring system to monitor the real-time monitoring of the settlement of housing under the shield, and through the use of timely communication tools to achieve information construction across the construction; definition of gravel mudstone composite formation shield excavation surface mudstone height and shield machine Cutter diameter ratio of the composite ratio λ, analysis of the average value of driving parameters with λ variation. The field test results show that the sleeve valve grouting can effectively control the settlement of the building. The automatic monitoring can reflect the deformation of the house caused by the shield advancement in real time and provide the basis for the construction feedback control. The mud shield meets in the gravel mudstone composite formation To the excavation warehouse pressure fluctuations too large, cutter torque, thrust increases, penetration and reduce the phenomenon. When λ≤0.15, the above phenomenon basically does not occur. When 0.15≤λ <0.6, the average of the parameters fluctuates the most violently and is very unfavorable to the settlement control. When λ≥0.6, the torque and the total thrust force further increase, Slight fluctuations and penetration will be further reduced. It is an effective measure to reduce the parameter fluctuation by taking the pressure control of shield excavation as an index instead of pursuing the propulsion speed, increasing the revolving speed and lowering the mud viscosity.